Process of modifying starch



E. H. HARVEY.

PROCESS OF MODIFYING STARCH. APPLICATION FILED MAY 13, 1920.

1,366,653., Patented Jan. 251921.

I awuM-to c m4 I Tum-r120 STATES PATENT orrlcs ELLERY H. HARVEY, OF LANSDALE, PENNSYLVANIA, 'ASSIGNOB 'I'O PERKINS COMPANY, A CORPORATION OF PENNSYLVANI$. I

GLUE

rnoonss or momrrrne srancn.

1,3ee,e53.' v

' Application flied my 13,

To ail whom it Be it known that I ELLERY I-I. HARVEY I citizen of the United states and resident of Lansdale, in the county of Montgomery and State of Pennsylvania, have invented certain new and useful Improvements in Processes of Modifyin Starch, of which the following is a speci cation.

My inventlon relates to Improvements in rocesses of modifying orconverting starch. eretofore' it has been common to modify or convert starch for various purposes by treating the same with various chemicals such as certain acids or alkalis. be modified or converted in this way to produce soluble starch, dextrin, etc., and if the treatment is'only carried a short way, the starch may be converted only to a relatlvely slight extent-so as to produce a starch base suitable for making vegetable wood veneer glue such as described in, Reissue Letters atent 13436 dated July 2, 1912, According to the present invention instead of modifying or converting the starch 26 by means of chemical reagents as heretofore done, I employ the action of electrolysis for this purpose, and prefer to stop the action may concem:

beforethe conversion or mo.d1fication has assed the soluble starch stage. I have 30 ound that if an electric current is passed through a liquid suspension of the starch in water, it apparently modifies or converts the starch toproduce various starch conversion roducts. In converting the starch electrically or electrolytically I prefer to mix the starch with water to form a liquidsuspension of the starch in water and while the bath is being agitated the current is passed therethrough, the strength of current and time depending upon the nature and kind of I starch used and thedegree of conversion desired. I preferably add to the suspension of starch in water a slight amount of acid in order to make the bath substantially conducting for the electric current although in some cases ordinary water may be used which contains as impurities sufiicient salts or alkaline or acid bodies to render the bath sufficiently conducting. The conversion carried out at substantially atmospheric pressure and substantially at atmospheric or room temperature and I preferably stop the action before any large starch has been converted to soluble starch so that it will be suitable as a base for makspeciflcation of Letters Patent.

The starch may part of the PatentecLJ an. 25, 1921. 1920. Serial No. ceases. 7

ing wood veneer glue as described in said Reissue Patent13436. As one specific example of converting socalled raw starch to increase its solubility and decrease 1ts viscosity to make a base for -the making of a veneer glue according to said Reissue Letters Patent 13436, I placed n a circular wooden tank like that shown in the accompanying drawing, which forms a part of this specification, a mixture of 6000 pounds of so-called rawcassava starch havmg a relatively high viscosity, and 24,000

ounds of water and iters of hydrochloric The tank 1 was rovide'd with an agitator 2 secured to a splndle 3 driven b pulley 4- so as to keep the bath in continuo 's agltation. The agitatbr 2 was arrange one arm tended to force the 1i and the other arm tended to orce it downwardly. I rovided in the bath 2,iron electrodes 5 an 6 connected to a suitable source of electrical energy indicated at 8 by suitmay be made of iron lates at out two feet square, but since the 11011 m y be slightly attacked, carbon electrodes may be used if. desired. The voltage used was about 110 volts andI found that after a direct ourable conductors 9. The electjpdes 5 and 6 ,rent of about 31} amperes had been passed through the bath while being continuously agitated, for about one hour, the starch had been suitably converted or degenerated for making 1glue aS described in said Reissue Letters atent 13436. The tank used was about sixteen feet indiameter. The small amount of hydrochloric acid was added merely to make the bath sufiiciently conducting. Itwill-be understood, however, that any other chemicals suitable for making the water bath sufiiciently conducting may be used, such as sulfuric acid or other acids, alkalis or salts. However, only a very small quantity is needed and'no such quantity is required as would ordinarily be used to convert the starch if the conversion was carried out purely by chemical action. By the use of suitable electrolyte, the starch may be added to the bath twoacid of 28% strength.

so that u1d upwardly easily converted into soluble starch and so I iscosity, and t e conversion of the starch may be stopped at any point desired by discontinuing the current and allowing the starch to settle and draining ofi the liquid trolyte for another batch. It will also be understood that the strength of current used and the time of treatment will depend upon the kind and nature of starch used and conversion desired. Apparently the action of the current causes a tearing apart .or splitting up of the aggregates of starchy matter within the starch granule whereby the starch becomes more easily soluble in water or caustic soda solutions or soluble in the same caustic soda solution to produce a; less viscous solution, but unless the treatment is carried very far as beyond the soluble starch stage the starch will still retain the general size and form or granule as when originally introduced. I find that my method is particularly adapted to the degeneration of starch for the making of a glue base for making veneer glue as described in said reissued Letters Patent 13436 and the conversion of the. starch is accomplished in a very much shorter time than if it was done by the use of-chemicals merely, and also without the use of any substantial amount ofexpensive chemicals. Furthermore according to my method not only may the conversion be quickly accomplished, but it is easily stopped at any desired point by turning off the cur rent, Although I have described my improvements in great detail and with respect to preferred emhodi'ments,-l do not desire to be limited to such details or embodiments since many changes may be made and the invention embodied in widely difierent forms without departing from the spirit and scope of the invention in its broader aspects.

What I claim as new and desire to secure by Letters Patent, is:

1. The improved process of producing modified or converted starch which consists in passing an electric current through .an

electrically conducting bath containing the pheric pressure and temperature untilthe desired modification or conversion of the starch is obtained by electrolysis.-

3. The improved recess of modifying or converting starch which consists in passing an electric current through a liquid suspension of the starch in water at substantially atmospheric pressure until the desired modification or conversion of the starch is obtained by electrolysis.

4. The improved rocess of modifying or converting starch w ich consists in passing an electric current through a liquid suspension of the starch in water at substantlally atmospheric pressure to modify or convert the starch whereby it will dissolve in caustic soda solutions to produce less viscous solutions and stopping the action before the starch has passed the soluble starch stage.

5. The improved process of modifying or converting starch which consists in passing an electric current through a liquid suspension of the starch in water at substantially atmospheric pressure to modify or convert the starch whereby it will dissolve in caustic soda solutions to produce less viscous solutions and stopping the conversion or modification before any large part of thestarch 

